Child seat and method for recognition of a child seat

ABSTRACT

In a child seat and a method for child-seat detection, a radio-identification chip, which is configured solely as a transmitter module, is introduced in the child seat, preferably in the fabric. Due to the automatically emitted radio signal, the child seat is detected by corresponding receiver devices in the vehicle.

BACKGROUND INFORMATION

A transponder system for child-seat detection is known from GermanPatent Application No. DE 198 21 501. This system utilizes radio signalsto detect a child seat, the child-seat detection in the vehicle seattransmitting a radio signal to the transponder in the child seat, whichthen retransmits this signal in changed form. The child-seatidentification is carried out on the basis of the retransmitted radiosignal.

SUMMARY OF THE INVENTION

The child seat and the method for child-seat detection according to thepresent invention have the advantage over the related art that theyprovide a simplified system for child-seat detection. It isdistinguished in that a radio-identification module, which includes anidentifier, is preferably introduced in the fabrics of the child seat.The radio-identification chip transmits a radio signal, which includesthe identifier on the basis of which the child seat is detected, thistransmission taking place continuously or intermittently, without anyrequest. For that reason, the radio-identification chip is configured astransmitter module only and has no receiver structures. On the otherhand, a receiver structure, but not necessarily a transmitter structure,is present in the vehicle seat. The radio identification according tothe present invention is therefore achieved solely by a radiotransmission from the child seat to the vehicle seat. Another advantageis that the simple, uncomplicated methodology applies to all child-seatmanufacturers, so that a child seat specified by the vehiclemanufacturer must not necessarily be purchased. Another advantage isthat no intervention in the design of the child seat is required which,if necessary, also allows retroactive fitting using appropriate fabrics.

The vehicle may additionally include a conventional child-seat detectionas it is known from the related art.

It is particularly advantageous that the radio-identification chip iswoven into the fabric itself. The radio-identification chip module maybe bonded to the conductive web strips as it happens in wire-bondingmethods. As an alternative, a flexible plastic foil, similar to aflexible circuit board, having attached connection pads may be used. Inboth cases the radio-identification chip and the connecting region arehermetically encapsulated. The energy for the radio-identification chipin the fabrics may be provided either by an energy store such as abattery or an accumulator, which is rechargeable, or by athermogenerator. Since the human body generates energy in the form ofheat on the order of several 10 watts, it makes sense to utilize aportion of this energy. Miniaturized thermogenerators, for instance, areable to obtain electrical energy from the temperature difference betweenthe body surface and the ambient environment. Thermogenerators aresimple electrical components made up of two different conductors orsemiconductors. They are joined to one another at one end in each caseand in this way form a thermo pair. If there is a temperature differencebetween the two sides of a thermo pair, an electrical voltage will begenerated due to the so-called Seebeck effect, and current will be ableto flow through a connected load, which in this case is theradio-identification chip module. A thermogenerator is made up of amultitude of thermo pairs, all of which are electrically interconnectedin series and arranged side-by-side, in meander-shape, in order toensure optimum space utilization. In this way, high overall voltages andelectrical outputs are achieved. In contrast to batteries, thesethermogenerators have very advantageous characteristics: They arewashable, robust, they are made of environmentally friendly materialsand have a practically unlimited service life. When thermogenerators areimplemented in textiles, it is important to select locations where theoccurring temperature differences between the inside and outside are ashigh as possible. For a reliable, constant energy supply the generatedtemperature profiles at moderate ambient temperatures and with thinclothing must be taken into account. Relatively low temperaturedifferences of four to six Kelvin are measured at the wrists, whichgenerally have low skin temperature. In contrast, the neck regionreaches very high values. A collar in close contact with the skingenerates temperature differences of 17 Kelvin, which makes this regionvery attractive for obtaining energy. However, this is in some respectsnot so attractive for a child seat. Nevertheless, the results generallyindicate that temperature differences of at least 5 Kelvin are attainedin the clothing, even at moderate ambient temperatures.

To achieve the highest possible temperature difference across thethermogenerator, it must be integrated directly into the fabric and anexcellent thermal transition to the skin has to be ensured. For itscoupling to the outside, thin copper platelets in each case are affixedto its cold and hot side. Copper is particularly suitable due to thefact that it has very high thermal conductivity. To prevent the copperfrom discoloring the skin, it is also galvanically coated by a thinlayer of gold or silver. The thermogenerator chip is encapsulated in awaterproof manner using polyurethane. The electrical contacts areconnected to the silver-coated copper wires, which are insulated withthe aid of polyester varnish and woven into the fabric. A buffercapacitor, which stores the generated energy, may be integrated directlyat the thermogenerator or some other spot in the clothing. In the caseof a temperature difference of 5 Kelvin across the thermogenerator chipmade of silicon, an electrical power output of 1.0 □watt per squarecentimeter is generated under a load and a no-load voltage of 10 voltper square centimeter. These values already suffice to supply awristwatch with energy. Higher outputs may be obtained by highertemperature differences and a larger active surface. A power output of10 to 300 □watt is sufficient to supply medical sensors with energy andto transmit the data to a recording device in a wireless manner.

The child-seat detection according to the present invention mayadvantageously be combined with other methods for child-seat detectionwith the goal of achieving plausibility or increased reliability of thechild-seat detection. For instance, it may be connected to a child-seatdetection that determines the child seat via the seat-pressure profile,for example with the aid of a sensor mat, or which has an opticalidentification system for child-seat detection, i.e., a video sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a first block diagram of the child seat according to thepresent invention.

FIG. 2 shows a schematic representation of the device according to thepresent invention.

FIG. 3 shows a flow chart of the method for child-seat detectionaccording to the present invention.

DETAILED DESCRIPTION

Apart from a direct mass determination in order to identify a child seaton the passenger side, there is the possibility of equipping the childseat with a transponder system. The so-called OC (occupantclassification) mat includes a transmitter and receiver antenna. Thechild seat has at least one or a plurality of transponder coils, whichreact to the signal transmitted by the OC mat and return a correspondingsignal, partially in encoded form. Via the receiver antenna it is thenanalyzed whether a child seat is located on the seat. Furthermore, it isascertained on the basis of an identification what type of child seat isinvolved and how it is positioned.

According to the present invention, another method for the contact-lessor contact-free detection or identification of child seats will now beintroduced. In this context a method and a child seat are to beprovided, which may be realized without major changes in the child seatitself. This allows every child-seat manufacturer to utilize themethodology of the transponder detection yet does not result incompetitive distortions.

According to the present invention, a radio-identification chip, whichwill then emit an identifier for this particular child seat, isintroduced into the fabrics of the child seat. The radio-identificationchip has no receiver device and is supplied by its own energy supply,namely either a thermogenerator or an energy store such as a battery. Itmay be provided that the energy store be rechargeable or exchangeable.More than one radio-identification chip may be used in a child seat. Theradio-identification chip is preferably woven into the textiles and isable to emit the radio signal on a permanent or intermittent basis. Themethod according to the present invention may be used in addition toother methods for child-seat detection such as analyzing a seat-pressureprofile or an optical identification. This allows a plausibilization ofthese results.

FIG. 1 shows a block diagram of the device of the present invention. Inthe child seat an energy store 1 is connected to a radio-identificationchip 2. Via an output, radio-identification chip 2 is connected to anantenna 3. It is possible for all three components to be arranged on oneelement. They may also be separately accommodated in the fabrics of thechild seat. In the seat of the vehicle, an antenna 1 is connected to areceiver module 5, which is connected to a control unit 6. Control unit6 is connected to an airbag control unit 7 to which a sensory system 9is connected as well. Airbag control device 7 is connected torestraining means 8.

Radio-identification chip 2 uses energy from energy storage 1 for itsoperation, which is a thermogenerator or a battery, and in this waycontinuously transmits identification signals via radio communicationusing antenna 3. Such an identifier is received by antenna 4 andtransmitted to receiver module 5, which performs signal conditioning viaamplification, mixing and filtering. Receiver module 5 then transmitsthe identifier as digital signal to the control unit or to processor 6,which compares the received identifier with stored identifiers so as toascertain whether it is an identifier emitted by a child seat. If achild seat was detected, control unit 6 transmits a signal to airbagcontrol device 7 that a child seat is located on the seat in question.In this case, airbag control unit 7 will not trigger the respectiverestraining means. Otherwise, in a trigger case that is detected bysensory system 9 such as acceleration sensors, airbag control unit 7would trigger restraining means 8 also for the seat on which the childseat is located.

The radio signal emitted by antenna 3 has only a limited range, so thatother receivers in the vehicle, in particular for the other seats, areunable to receive this radio signal. This may be achieved by using avery high transmitting frequency, for example, or a very lowtransmitting capacity. In particular the weak transmission output isadvantageous since it places a low load on energy store 1 and is alsonon-critical with respect to electromagnetic compatibility. Theacceptance of such a radio-identification chip will also increase if theenvironmental impact of the emitted radio signals, and especially theeffect on a small child seated in the child seat, are negligible.

FIG. 2 shows a schematic representation of the device according to thepresent invention. A child seat 203 having the transmitter unitaccording to the present integrated into the fabric is arranged on avehicle seat 201. Through contactless measurement 204 and with the aidof receiver 202, the vehicle seat detects the presence of a child seaton seat 201. This is recognized in the control unit ECU. The controlunit ECU then transmits a corresponding signal to an airbag control unitAB-ECU checking whether the particular airbag is to be switched off oron. As a function thereof, airbag control unit AB-ECU then triggersrestraining means 205.

FIG. 3, in a flow chart, shows the sequence of the method for child-seatdetection according to the present invention. In method step 301,radio-identification chip 2 transmits the identifier by means of a radiosignal, with the aid of antenna 3. In method step 302, receiver 5, usingantenna 4, receives this signal and transmits it to control unit 6. Inmethod step 303, control unit 6 determines on the basis of theidentifier whether a child seat is involved. If this is detected to bethe case in method step 304, the airbag control unit will be triggeredcorrespondingly in method step 306.

However, if it has been detected in method step 304 that no child seatis involved, the method is ended in method step 305.

Furthermore, this system offers the possibility of providing redundantinformation in addition to mass-determining sensors or pressure-foilsensors. The receive system on the vehicle side may just as well beintegrated directly into the vehicle seat or into the seat back or theseat cover, in this way simplifying the mass production since theintegration of foil-pressure sensors is very costly and may entail largetolerances during installation. An H-point increase is not given eithersince the characteristic of the fabric does not change. Another possibleapplication is the integration of this electronics system in variousseat pads. In the case of pressure foils, this results in blurring ofthe input signal. With appropriate identification it is possible toinform the control unit of this fact, and corresponding modificationsmay be made. This would prevent faulty classifications and possiblyavoid de-energizing the airbag for persons as a result of faultyclassifications.

The system according to the present invention preferably operates in theISM frequency range or some other frequency range that is suitable forsuch short-range applications.

1. A child seat having radio-based identification, the child seatcomprising: at least one radio-identification chip configured as atransmitter module and situated in the child seat, the at least oneradio-identification chip having a specific identifier for transmissionvia a radio signal, wherein the at least one radio-identification chipis woven into fabrics used for the child seat; and a thermogenerator forsupplying the at least one radio-identification chip with electricalenergy.
 2. A method for detecting a child seat, the method comprising:supplying by a theremogenerator an electrical energy to aradio-identification chip; and detecting the child seat with the aid ofa radio signal produced by the radio-identification chip that isautomatically transmitted from the child seat.
 3. The method accordingto claim 2, wherein the radio signal is emitted on a permanent basis. 4.The method according to claim 2, wherein a seat-pressure profile isadditionally utilized for child-seat detection.
 5. The method accordingto claim 2, wherein an optical identification system is additionallyutilized for child-seat detection.